The present invention relates to a weld design to fix a ball to a tube to form an armature assembly for a fuel injector.
In known applications, steel balls are welded to tubes in a fuel injector armature assembly such that the weld joint typically is made at the end of the tube, forming a butt type weld. The ball is typically constructed from high chromium and high carbon steel alloy, such as 44xc2x0 C., and is difficult to weld to the armature. The excess carbon in 44xc2x0C. (1 percent) exceeds the solubility limit of carbon in iron, which forces carbides to form during alloy manufacture. During the welding process, rapid cooling often leads to cracked welds. Further, adding excess heat during the welding can distort the ball roundness, which leads to improper ball seating in the seat during operation of the injector.
It would be beneficial to provide an armature/ball assembly which can be manufactured without introducing excess heat during the welding process, and in which a sufficiently strong connection can be formed between the tube and the ball.
Briefly, a fuel injector is provided. The fuel injector comprises a metering member for delivering fuel from a delivery end of the fuel injector. The metering member comprises a seat disposed proximate the delivery end of the fuel injector; and an armature assembly. The armature assembly includes a longitudinal axis, a seating element disposed generally along the longitudinal axis, and an elongated tube. The elongated tube has a first end, a second end, and a tube channel extending from the second end toward the first end. The first end has a first portion connected to the seating element with at least one weld and a second portion disposed distal from the longitudinal axis from the first portion. The armature assembly is reciprocably disposed within the fuel injector between a closed position wherein the seating element is biased against the seat and an open position wherein the seating element is disposed away from the seat.
Additionally, the present invention provides an armature assembly. The armature assembly comprises a longitudinal axis, a seating element disposed generally along the longitudinal axis, and an elongated tube. The elongated tube has a first end, a second end, and a tube channel extending from the second end toward the first end. The first end has a first portion connected to the seating element with at least one weld and a second portion disposed distal from the longitudinal axis from the first portion. The armature assembly is reciprocably disposed within the fuel injector between a closed position wherein the seating element is biased against the seat and an open position wherein the seating element is disposed away from the seat.
Also, the present invention provides a method of manufacturing an armature assembly. The method comprises providing an elongated tube having a longitudinal axis extending therethrough, a first end having a first portion and a second portion located distal from the longitudinal axis relative to the first portion, a second end, a tube channel extending from the second end toward the first end; and fixedly connecting a seating element to the first portion with a connection.